MOBILE, Alabama -- Brace yourself for ambiguity. Making medical decisions for yourself or others rests on probability, not certainty.

But there’s a way through this field of ambiguity. It requires accepting the uncertainty yet still making the effort to find out what is knowable, and then taking the Socratic advice to understand yourself and what is most important to you. Your particular mindset — your ingrained predispositions — plays a crucial role in arriving at the wisest decision possible for you.

This is the helpful advice that physicians Jerome Groopman and Pamela Hartzband offer in “Your Medical Mind: How to Decide What is Right for You.” The authors slay the illusion that there’s always one best decision to make in choosing medical treatments — if only we could discover it. Their book covers the broad range of medical decisions, from deciding whether to take medication for treating high blood pressure all the way to choosing resuscitation or intubation in a final illness.

Groopman is Recanati Professor of Medicine at Harvard Medical School and chief of experimental medicine at Beth Israel Deaconess Medical Center. Hartzband is an assistant professor at Harvard Medical and an endocrinologist at Beth Israel Deaconess.

Groopman has an unusual dual vocation. He is both an oncologist and a staff writer for The New Yorker. He has the advantage of being a pellucid writer. Medical decisions, especially ones that can extend or end a life, can founder on information that is murky or even incomprehensible. The authors of “Your Medical Mind” shed light for us.

Your Medical Mind: How to Decide What Is Right for You By Jerome Groopman and Pamela Hartzband Penguin Press, $27.95

Reviewed by FRANK HURLEY Correspondent

“Despite many scientific advances,” they write, “the unsettling reality is that much of medicine still exists within a gray zone where there is no black or white answer about when to treat or how to treat.

“Often, there are several different approaches to treatment, each with its own risks and benefits. The best choice for an individual may be anything but simple or obvious.”

Statistics — for example, the percentage of patients that have benefited from a particular treatment — help sketch in the context for a medical decision. They can provide useful information. But then, what are you willing to put yourself through for a corresponding level of probability?

This dilemma becomes even more agonizing if you are acting as a surrogate for someone else, perhaps a child, or another adult no longer capable of making crucial medical decisions.

“If medicine were an exact science, like mathematics,” caution Groopman and Hartzband, “there would be one correct answer for each problem. Your preferences about treatment would be irrelevant to what is ‘right.’ But medicine is an uncertain science. Although presented as scientific, formulas that reduce the experience of illness to numbers are flawed and artificial.”

After all is known that is available to be known, the authors emphasize that medical decisions need to be tailored to the individual patient. What is the patient’s ingrained mindset? More generally, how does that person approach life?

In their research for this book, Groopman and Hartzband uncovered three rubrics that help in defining a patient’s mindset. First, is the patient (yourself or someone for whom you are acting as a surrogate) a minimalist or a maximalist? Does the patient lean toward doing the most possible that can be done? Or does the patient lean toward doing the least possible — taking baby steps?

Next, is the patient a believer or a doubter? Does the patient readily accept advice? Or is the patient a natural-born skeptic?

Third, is the patient inclined toward naturalism or technology? Does the patient prefer more traditional or natural remedies? Or does the patient want the latest that science and technology can offer?

The authors are candid in summing up their experience: “Writing this book changed us. It changed how we, as physicians, help our patients make decisions about treatment.

“Each day at work, as we speak with people facing different treatment options, we find ourselves using the terms that arose from this book: minimalists and maximalists; believers and doubters; naturalism or technology orientation. Writing this book also changed how we weigh options about our own health, defining and showing us the origins and evolution of our preferences.”

The ambiguity surrounding medical decisions remains. But this helpful book can prepare us to deal with that ambiguity more skillfully.

Frank Hurley lives in Mobile and wrote the “Talk About Books” column for the Press-Register in the 1980s.